Call flow system and method for use in a VoIP telecommunication system

ABSTRACT

A method of establishing a communication link between a mobile terminal of a wireless network and a subscriber of a network, such as an enterprise network, and/or a residential network.

FIELD OF THE INVENTION

The present invention relates to telecommunications, and moreparticularly telecommunications including enterprise servers, wirelesscommunications, and the interoperability of communication technologies.

BACKGROUND OF THE INVENTION

Corporations are increasingly relying on the use of cellular technologyby their employees. Yet enterprises do not have adequate means tocontrol cellular service, in terms of costs, Quality of Service, andcorporate monitoring. This is because cellular service is independentlymanaged and controlled by wireless carrier networks with no connectivityto the enterprise voice and data networks, as shown in FIG. 1.

Enterprises today control their enterprise fixed voice and datanetworks, as is shown on the left of the diagram. They own and managetheir own PBXs, within each branch, and between branch offices. Theyalso own and manage their own data networks and corporate LAN/WAN. Theypurchase bulk voice minutes and data capacity from land line carriers,or from other providers that have purchased bulk minutes and datacapacity from carriers, to connect branch offices, using public IPNetwork providers (e.g. MCI, Sprint, L3, etc.) for Data and Voice overIP (VoIP).

With this invention, the enterprise is able to equally extend thisparadigm to cellular service by connecting the public wireless voice anddata network (on the right side of the diagram) into the enterprise.This is shown in FIG. 2. The gateway server inter-connects the carrier'sMobile Switching Center (MSC) that manages cellular voice traffic aswell as the carrier's Serving GPRS Support Node (SGSN) that managecellular data traffic, with the enterprise's voice and data network.

SUMMARY OF INVENTION

The invention achieves technical advantages as a method of establishinga communication link between a mobile terminal of a wireless network anda subscriber of a network, such as an enterprise network, and/or aresidential network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an independently managed and controlledwireless carrier network, and an independently managed corporateenterprise network;

FIG. 2 is a diagram of a conventional network with an enterprise networkgateway server, according to the invention, connected to a wirelesscarrier network;

FIG. 3 is a diagram of a gateway server system accordingly to onepreferred embodiment of the present invention;

FIG. 4A is a diagram of an enterprise data and voice network operablyconnected using the gateway server system using pure enterprise callcontrol according to one preferred embodiment;

FIG. 4B is a diagram of an enterprise data and voice network operablyconnected using the gateway server system using split call controlaccording to one preferred embodiment;

FIG. 5 depicts a network architecture according to another preferredembodiment using VoIP systems;

FIG. 6 is a call flow diagram for call origination according to oneembodiment of the present invention;

FIG. 7 is a call flow diagram for effecting call delivery using VoIPsystem according to another preferred embodiment of the presentinvention;

FIG. 8 is a call flow diagram for effecting mobile termination usingVoIP according to another preferred embodiment of the present invention;

FIG. 9 is a diagram of a network architecture for a Legacy (TDM) networkaccording to another preferred embodiment of the present invention;

FIG. 10 is a diagram of a next generation IMS architecture that isbackwards compatible with legacy cellular networks based on existingcellular protocols;

FIG. 11 is a diagram of a conventional legacy network architecture thatdoes not support IM;

FIG. 12 depicts a Packet Engine according to another preferredembodiment of the present invention allowing a call server to detectDTMF digit events on the call path;

FIG. 13 depicts one embodiment of the Packet Engine consisting of a userspace;

FIG. 14 depicts a Linux kernel module of the Packet Engine;

FIG. 15 depicts the current IMS standard definition;

FIG. 16 depicts one exemplary embodiment of the invention for IMSservice;

FIG. 17 and FIG. 18 depict a gateway server carrier (GS-C) configured asan IMS standard-compliant SIP, and associated algorithm; and

FIG. 19 depicts an algorithm for receiving incoming calls on variouslines that are to be directed to a subscribers mobile phone.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Effectively in one preferred embodiment of the invention, a gatewaymobile server is provided that runs a turnkey cellular system that doesnot include any radio network components. The gateway mobile server isappropriately scaled down to the smaller subscriber base of a largeenterprise, compared with that of a public carrier. The gateway mobileserver advantageously supports call routing between a legacy, hybrid orIP-PBX, and the public cellular network in support of theenterprise/virtual operator business model.

This solution ultimately enables enterprises to change the way theypurchase cellular service from cellular operators by enablingenterprises to effectively become a Mobile Virtual Network Operator(MVNO) for their own employees, and ultimately even sell cellularservice external to the enterprises corporation. Thus, the enterprise isable to purchase discount bulk rate cellular minutes of use from apublic cellular carrier, and “resell” them internally to their costcenters, or externally to other entities. The solution effectivelyenables the enterprise to “plug-in” cellular service akin to how localand long distance are connected to the enterprise's PBX. The result isthat enterprises can consume minutes of use from public cellularcarriers and pay for those minutes at the end of a time period, forexample at the end of the month. A single relationship can exist betweenthe cellular carrier and the enterprise, rather than multiple individualsubscriptions between the carrier and enterprise employees (where thecarrier is forced to treat them as ordinary consumers). This embodimentof the invention also facilitates the situation in which a singleservice provider can provide local, long distance, cellular and internetservice to an enterprise. Ultimately the enterprise can become its ownservice provider with its own Home Location Register (HLR) and HomeSubscriber Server (HSS) operating on and interconnected with the publicnetworks. Thus, employees making/receiving voice calls and data sessionscan be roaming on cellular carrier networks, which will charge theenterprise based on their usage.

The voice gateway component in this embodiment of the inventioncomprises a hybrid gateway router, combining the traditional routingfunctionalities of a Wireless Gateway Mobile Switching Center (GMSC)with the admission control and routing functionalities of an IMS SIPApplication Server proxy and/or H.323 gatekeeper in addition tofunctionality for call management and control in the enterprise spacebased on SIP and/or H.323.

All signaling is transported over IP instead of SS7 where possible usingprotocols, such as SIGTRAN. In cases where IP signaling is notavailable, SS7 may be required to connect with the public cellular andcarrier networks. In addition, the invention supports functionality nottraditionally associated with a Wireless GMSC. This includes support for3GPP/2 SIP and/or H.323.

The present invention provides support for 3GPP/2 SIP, GSM MAP, CAP,ANSI-41/WIN and AIN protocols, converts between them and maps toindividual SIP network elements in the enterprise network. Support forsignaling is via SIGTRAN with high reliability over IP connectionsinstead of traditional and expensive SS7 links.

Various embodiments of the invention provide technical advantagesincluding:

Interconnection algorithms between carrier network telecom protocols andspecific enterprise PBX services platforms, including enhancements tostandard cellular network nodes including GMSC, SCP, GGSN:

-   -   Nodal inter-connection algorithms    -   Various configurations        -   Enterprise-hosted, Enterprise Managed:    -   The solution is hosted entirely within the enterprise and        controlled by the enterprise        -   Enterprise-hosted, Shared Management:        -   The solution is hosted entirely within the enterprise and            controlled by both the enterprise and remotely by the            carrier        -   Enterprise hosted, Carrier Managed:        -   The solution is hosted entirely within the enterprise and            controlled remotely by the carrier        -   Carrier-hosted, Enterprise Managed:        -   The solution is hosted at the carrier site and controlled            remotely by the enterprise        -   Carrier-hosted, Shared Management:        -   The solution is hosted at the carrier and controlled by both            the enterprise and remotely by the carrier        -   Carrier-hosted, Carrier Managed:        -   The solution is hosted at the carrier site and controlled by            the carrier        -   Shared-hosted, Shared Management:    -   A component of the solution is hosted, managed and controlled at        the carrier site, and a component of the solution is hosted,        managed and controlled at the enterprise site.

Routing of dialed digits from carrier network to enterprise systemwithout modifying carrier software, using existing intelligent networkand/or IMS signaling and data messaging techniques.

Method for reducing/eliminating of PSTN interconnect charges betweencarrier and enterprise, enabling:

-   -   Low cost mobile-to-mobile calls even when served by different        carriers        -   This may be achieved by routing the calls from the carrier            network into the enterprise using VoIP technology, and thus            bypassing the PSTN network    -   Low cost mobile to IP voice client calls (mobile to PC client,        Skype, etc.)

Methods for increasing enterprise-grade availability via a cellularinterconnection gateway:

-   -   Methods for maintaining enterprise call handling capabilities        when individual enterprise network nodes fail        -   For example, when a call is originated from the cellular            network and its control messages are sent to the gateway            server for processing, if the gateway server detects that            the PBX system is not available or out of service, the            gateway server can instruct the cellular network to route            the call directly. The gateway server may modify the digits            if necessary. The cost of the call may be higher than if            routed through the PBX, however the call will nevertheless            be connected. Once the PBX becomes available, the gateway            server can direct subsequent calls through the enterprise            network.

Enterprise MVNO Business Framework

-   -   Enabling large enterprises to become cellular service providers        for their employees    -   Spinoff business opportunities for sale of cellular voice/data        services PBX evolution for wireless interconnection

MVNO Infrastructure

-   -   Framework, methodology and mechanisms for increasing MVNO        value-chain service capabilities    -   Framework to enable MVNOs to support own core network switching        and services through an existing carrier's wireless access        infrastructure

Integrated Services Capabilities Framework

-   -   Enabling improved integration and customization of enterprise        applications on public carrier networks    -   Framework enables the migration of business solutions to        customized enterprise environment, away from generic carrier        offerings using enterprise information systems not available to        carrier networks, e.g.        -   Local Presence & Availability information        -   Enterprise badging and security systems            -   For example, with the call control managed out of the                enterprise rather than the cellular network, the                enterprise can connect disparate systems to enforce                policy controls such as disabling an employee's cellular                phone when they badge out of the office for the evening,                or changing the charging codes such that the employee                will be charged for calls made after they have badged                out of the office for the evening, or limiting the                employee to 250 minutes of personal phone calls after                badging out for the evening, or restricting                international calling, or enabling international calling                to a single country such as the country of one's family,                etc.

Intelligent Least Cost Routing Techniques

-   -   Algorithms for enabling intelligent Tail-end Hop-off of calls        and data sessions within the enterprise's network        -   Including methodology for inter-office (e.g. international)            call routing when local PBX is out of service        -   Tail-end hop-off enables a call from one country to another            country to be routed over a least-cost network to a            connection point in the destination country, from which a            local call is established and connected with the            international least-cost route. The result is a lower-cost            call to the destination.

Data Session Management

-   -   Similar to the ability to route voice calls into the enterprise        which are then subject to enterprise voice policy, the invention        describes the methodology and support for the routing of data        sessions from the public network directly into the enterprise.        By including a GGSN function within the enterprise and connected        with the cellular carrier's SGSN, a secure tunnel can be        established between the carrier and the enterprise networks. The        GGSN component can be split among two components of the Gateway        Server: One component located in the carrier network (within the        GS-C), and a second component located in the enterprise (within        the GS-E). Similarly this can be achieved with a Home Agent        function located within the enterprise and connected with the        carrier's Foreign Agent for CDMA networks. As such, the        invention:        -   Eliminates the need for VPN software to be launched on the            mobile device Subjects the mobile device to enterprise data            policy including security and firewalls no matter where the            device is located, and without the need for user            interaction—all data sessions are routed through the            enterprise's corporate network and firewalls        -   Enables software applications to be embedded in wireless            devices that can be launched remotely to, for example,            destroy data on the device should the unit be lost or            stolen—e.g. Poison Pills

The present invention in one embodiment includes a software/serversystem that advantageously provides a cost effective and transparentmeans to connect enterprise employees' cellular phones to theircorporation's PBX. The solution provides corporations with the abilityto achieve, with regular single-mode mobile phones used by employeeswithout requiring any special dialing sequences, the same PBX basedbenefits now provided for fixed office landline phones. The solutioncreates a multi-dimensional paradigm shift in the enterprisetelecommunications market that is expected to change the way enterprisespurchase and integrate cellular service with their PBX as well as theway carriers compete for all phone services to the enterprise.

The solution provides a unique product and business concept that ishighly strategic for enterprise customers and channel distributionpartners. Mobile operators have the opportunity to benefit fromenterprises' need for operational control, efficiency and flexibility.The solution drives competitive advantage, higher market share andincreased revenues for network operators by extending the cellularnetwork and its call control into the enterprise.

One implication of moving the call control into the enterprise is thatthe invention enables the enterprise to control theircommunications—enabling the enterprise to track, monitor and even recordvoice conversations that occur on public carrier networks. Theenterprise will be able to enforce policy-based call routing foremployees making and receiving calls on public cellular networks. Thismeans they can allow/prevent calls based on specific criteria such asdestinations, time of day, external stimuli (e.g. active employeebadge), other circumstances. As a result, corporations submitting tocontrol-procedure legislations such as Sarbanes-Oxley will now have theability to manage and control cellular communications in line with theirlandline (PBX) and data networks (e.g. e-mail traffic).

The gateway server transparently extends the cellular network directlyto the PBX in the enterprise, ultimately enabling the enterprise toequally ‘plug’ cellular service into their PBX from a choice ofproviders, alongside their local and long distance landline service. Inthe enterprise, the server according to one aspect of the presentinvention is a mobility gateway that enables the enterprise to manageits own cellular services and costs as well as to deploy customizedmobility solutions to bridge their internal business applications andprocesses with mobile devices. The architecture addresses the extensionof the PBX control over both cellular voice and data systems, inaddition to the current PBX control over land line voice. The approachof the present invention is a networking solution versus adevice-centric solution, and does not require the enterprise to deployand manage complex RF (radio frequency) components or purchasespecialized mobile devices.

For the enterprise, the solution enables them to manage and controltheir cellular services & costs by routing all employees' cellular voiceand data calls through their corporate PBX network, while simultaneouslyenabling them to deploy customized and secure mobility solutionsintegrated with their internal IT systems. For the mobile operator, thesolution enables them to capture market share, grow revenues, reduceoperational expenses and reduce churn in the highly profitableenterprise segment.

Referring now to FIG. 3, there is shown a gateway server at 10 accordingto one preferred embodiment of the invention.

The gateway server:

-   -   Enables the enterprise to manage and control its cellular        service.    -   Enables the enterprise to achieve significant overall cost        reductions for telecommunications.    -   Includes an overall platform and architecture for improved and        integrated wireless enterprise solutions.    -   Drives convergence between the enterprise's cellular and Voice        over IP (Internet Protocol) infrastructure.

The gateway server 10 leverages the benefits of Voice over IP withcellular to extend the cellular network into the enterprise. The gatewayserver 10 addresses both cellular voice and data, and is a networkingsolution that works together with the enterprise's existing PBX,performing mobile call control functions (routing and services).

Additionally, the gateway server 10:

-   -   Bridges the enterprise PBX and public cellular environments to        enable telecom applications for the cellular user, such as        short-code dialing (e.g. 4 and 5-digit dialing), one number        service (one phone number for the desktop and cellular phone),        single voice mail box.    -   Enables the enterprise to leverage their existing telecom assets        for cellular use (e.g., least-cost routing over corporation's        VoIP or leased-lines network for discounted long distance; use        of existing PBX voicemail system).    -   Is an application platform for deploying mobile IT applications.        Either the enterprise IT department or a Systems Integrator can        develop and integrate specific applications to interface with        the corporation's cellular devices.        -   For example, the enterprise can choose to replace the            deskphone of an office employee with an inexpensive mobile            phone. For this employee, when they ‘badge-out’ of the            building at the end of the day, the enterprise security            badging system can be used to inform the gateway server to            de-activate the mobile phone, until the employee returns to            the office and ‘badges-in’ the next morning. Alternatively,            the gateway server can track and record the calls made            outside the office hours, and enable the enterprise to            charge them to the business, to the employee, or record them            as a corporate benefit.    -   Provides a single control point for the IT organization to        monitor and control cellular usage and services—all cellular        calls can be tracked and recorded in the enterprise's PBX        system.

The gateway server may be software-only solution that can execute onstandard, inexpensive Linux platforms. The gateway server may consist ofa mobile core network (for call handling and routing) and servicesnetwork (voice and data services such as PBX-based short code dialing,voicemail, conference calling, VPN, etc.) components. It may beappropriately scaled down to the smaller subscriber base of adecentralized large enterprise, in the order of hundreds to severalthousand subscribers, compared with carrier systems that manage manymillions of “centralized” subscribers. The gateway server is designed tobe managed and maintained by the same IT group that currently managesthe enterprise's PBX system.

The gateway server in some aspects is a cellular system which does notrequire or include any radio frequency network components—which arehighly complicated and expensive to deploy and manage. Campus radionetworks, whether cellular, Wi-Fi or other, require highly skilled anddedicated resources to maintain and ensure network stability for theenterprise's critical voice and data communications, whilesimultaneously managing their spatial co-existence with live publiccarrier radio networks overlapping the enterprise campus.

Instead, the invention includes a method for combining the technologyfor enabling enterprises to integrate its call control and services witha proven business model (MVNOs) that further enables the enterprise tonegotiate with carriers for a reasonable discounted price to use thecarrier's professional nationwide cellular network. To the carrier, thismaintains large numbers of high-value enterprise customers locked in ontheir networks, while reducing their costs of acquiring and maintainingindividual subscribers.

One network architecture implementing an aspect of the present inventionis shown in FIG. 4. From an IT organization perspective, the gatewayserver 10 appears as an extention to the PBX. To the cellular network,the gateway server 10 appears as a standard in-network endpoint fordelivering calls. To the enterprise PBX, the gateway server 10 appearsas a set of standard PBX endpoints (e.g. deskphones, or IP clients). Thegateway server 10 mediates between the two disparate sets of networkprotocols and state machines.

The gateway server 10 includes the network functions for both voice(gateway MSC) and data (gateway GPRS Support Node or Home Agent), VoIPcapability for interconnecting the mobile network with the enterprisethereby eliminating PSTN interconnect charges, a billing gateway, and anext-generation Network Services gateway (platform enabling third partyvalue added services for the enterprise (e.g. mobile phoneactivation/de-activation, corporate directory integration) based on IMS(IP Multimedia Subsystem). It also includes the element managementsubsystem (EMS) and a service management subsystem (SMS) for theoperational support system (OSS). The following Legend identified someof the terms used in FIG. 4.

Legend

-   -   GPRS: General Packet Radio Services—Provides mobility        management, session management and transport for Internet        Protocol packet services in GSM cellular packet networks.    -   GSM: Global System for Mobile Communications (GSM) is the most        popular standard for mobile phones in the world. GSM is both an        air interface and networking protocol. In the US this protocol        is used by T-Mobile and Cingular. The most popular alternative        combines the CDMA (Code Division Multiple Access) air interface        protocol and ANSI-41 networking protocol that are used in the US        by Verizon Wireless and Sprint.    -   HLR: Home Location Register—The central database that contains        details of each mobile phone subscriber that is authorised to        use the cellular core network.    -   IETF: Internet Engineering Task Force—Is charged with developing        and promoting Internet standards, in particular, those of the IP        protocol suite    -   IP: Internet Protocol—A data-oriented protocol used by source        and destination hosts for communicating data across a        packet-switched internetwork    -   ISDN: Integrated Services Digital Network—A type of circuit        switched telephone network system, designed to allow digital        transmission of voice and data over ordinary telephone copper        wires    -   ISUP: ISDN User Part—Part of the Signaling System #7 which is        used to set up telephone calls in Public Switched Telecom        Networks.    -   MAP: Mobile Application Part (MAP)—A GSM protocol that provides        an application layer for the various nodes in the core mobile        network to communicate with each other in order to provide        services to mobile phone users    -   MSC: Mobile Switching Center—The component of a cellular system        that carries out switching functions and manages the        communications between mobile phones and the Public Switched        Telephone Network.    -   PRI: Primary Rate Interface—A telecommunications standard for        carrying multiple voice and data transmissions between two        physical locations.    -   PSTN: Public Switched Telephone Network—The concentration of the        world's public circuit-switched telephone networks, in much the        same way that the Internet is the concentration of the world's        public IP-based packet-switched networks.    -   SGSN: Serving GPRS Support Node—The component of a cellular        system that keeps track of the location of an individual mobile        station and performs security functions and access control for        Internet Protocol packet services in GSM cellular packet        networks.    -   SIGTRAN: The name given to an IETF working group that produced        specifications for a family of protocols that provide reliable        datagram service and user layer adaptations for SS7 and ISDN        communications protocols.    -   SS7: Signalling System #7—A set of telephony signalling        protocols which are used to set up the vast majority of the        world's PSTN telephone calls    -   TDM: Time Division Multiplexing—A method for sending multiple        digital signals along a single telecommunications transmission        path    -   VoIP: Voice over Internet Protocol—The routing of voice        conversations over the Internet or any other IP-based network.

Configurations: The solution enables various configurations to bedeployed.

-   -   a. Pure enterprise call control in which the GS is located at        the enterprise site (GS-E) as shown in FIG. 4A (denoted as GS).        The GS-E interfaces with the cellular network nodes supporting        SS7 and SIP or other messaging with the carrier network. The        carrier network must be able to address the GS-E in order to        send and receive messages.    -   b. Split call control between carrier and enterprise in which        the GS located at the enterprise (GS-E) interacts with a GS at        the carrier (GS-C) as shown in FIG. 4B. The connection between        the GS-E and the GS-C can be SIP or other protocols. This        configuration typically enables the carrier network to have a        central point of control for interacting with multiple        enterprises, and may not require the use of SS7 messaging to the        enterprise—instead it is possible to have a secure IP connection        supporting SIP. This is also useful for offering a Centrex        solution for interconnecting with a carrier-hosted PBX, or for        interconnecting a carrier-hosted GS with enterprise-hosted PBX        systems. The GS-C supports an SS7 point code multiplexer in        which only one or two point codes are needed to address all        enterprises, since the GS-C can identify for which enterprise        the message is intended. The GS-E is able to provision the GS-C        automatically over the IP interface to manage subscribers, e.g.        to add new pilot DNs for new subscribers. In this case the        triggers used by the originating and terminating triggers used        in the cellular network for routing the calls to the GS-C can        add identifying information of the specific enterprise in the        triggering messages (e.g. ORREQ). Alternatively the GS-C can        identify the enterprise based on the calling party information.

The following description is based on FIG. 4A and illustrates oneoperation of the invention. When an employee originates a call, theinformation is transmitted to the MSC where the subscriber's profile isexamined. The subscriber profile, previously downloaded to the MSC fromthe HLR when the subscriber activated and registered on the network,contains information that might say they have no voicemail service(since they are using the enterprise voicemail system), no three-waycalling capability (since they are using the enterprise conferencebridge capabilities), and have an Intelligent Network trigger for calloriginations, terminations and mid-call triggers. These triggers directthe MSC to query an SCP (Service Control Point) to analyze the digitsdialed and decide on how to continue to route the call. The SCP isaddressed using standard SS7 point codes. Alternatively, in an IMSarchitecture, the SCP can be an IMS SIP Application Server that isaddressed via IP addressing instead of an SS7 point code. The gatewayserver acts as the SCP and receives the message where it communicateswith the PBX to determine the routing of the call based on criteria suchas whether the call should be directed into the enteprise to send to alocal device, redirect over corporate least-cost methods, requiresmonitoring, or if the call should be routed directly by the carrier if,for example, the destination is to another subscriber on the samenetwork in the same calling area and does not need to be monitored. Thegateway server then responds to the MSC with the routing instructions.In the case where it has been decided to route the call into theenteprise, the MSC may be instructed to route the call over the PSTNnetwork, or alternatively and preferred, the MSC may be instructed toroute the call to a soft-switch which will connect the cellular TDM callwaiting in the MSC to a Media Gateway which will convert the TDM to VoIPand route the IP-based voice traffic to the enterprise. The media isthen redirected at the enterprise to the destination by either thegateway server or the PBX. In some cases, the gateway server may act asa back-to-back user agent (B2BUA) to the PBX in which the incoming callfrom the MSC is directed to be routed to a destination that is the B2BUAvia the PBX. The gateway server, acting as the B2BUA, can then establisha new call leg to the original destination through the PBX (based on theinformation received when the gateway server was acting as the SCP/IMSSIP Application Server), and then connect the incoming call from the MSCto the new call leg.

Current enterprise PBX systems are developed to be ‘enterprise grade’ interms of their reliability and availability, compared with carriernetwork systems which are ‘carrier grade’ with failover solutions toprevent or minimize interruption of service. Enterprise PBX systems areby design not as reliable as carrier networks. With the gateway serversolution of the present invention, overall system availability isincreased as the gateway server intermediates between the carrier andenterprise networks. If the PBX goes down, the gateway server 10 caninstruct the carrier to route calls on behalf of the enterprise untilthe PBX is back in service. In the event that the gateway server 10should go out of service, the architecture of the invention is such thatthe carrier network will automatically take over the calls, with onlynominal delays in routing (for example, a timeout event may occur in theMSC, after which the MSC will continue).

Many cellular carriers today allow free calling between subscribers onthe same networks (e.g. Verizon to Verizon, T-Mobile to T-Mobile). Thisis partly because the call is maintained within the cellular carrier'sown network, thus no PSTN (Public Switched Telephone Network)interconnect charges apply to the carrier. In addition, to call from acellular phone on one carrier to a cellular phone on another carrier, orfrom a cellular phone to a landline phone requires the call be routedthrough the PSTN, thus incurring PSTN interconnect charges to thecarrier.

One architecture of the present invention as shown in FIG. 5 employsVoIP (Voice over Internet Protocol) to interconnect the carrier'scellular network, via a managed IP network or the Internet, with theenterprise network, eliminating PSTN interconnect charges to the carrierwhere allowed (certain countries do not allow bypassing PSTNinterconnect). As a result, employing this solution enables cellularcalls from an enterprise user on one cellular network to connect withanother enterprise user on a different cellular network withoutincurring PSTN interconnect charges for either cellular carrier therebyreducing the cost for the cellular carriers to service the enterprisecalls. This is because the call is routed by the gateway server from thefirst cellular carrier into the enterprise using VoIP, and from theenterprise out to the terminating cellular carrier using VoIP.

Similarly, cellular calls from enterprise users to landline phones arealso transitioned from the cellular network to the enterprise over VoIP,and are connected with the PSTN at the enterprise's PBX instead of beingconnected to the PSTN from the cellular network. Again, this reduces thecost for the cellular carrier to service enterprise calls.

For the enterprise, PSTN interconnect charges are included as part ofthe landline subscription. North American landline calling plans aretypically ‘all-you-can-eat’, with no per-minute charges for local PSTNinterconnection. In Europe and other parts of the world, landline callsare charged per time interval (e.g. per minute, or per 6-secondinterval), however at a substantially lower connection charge than forcellular calls.

The diagram of FIG. 5 outlines the architecture using VoIP between thecarrier and the enterprise. The Gateway Server-Carrier (GS-C) is locatedin the carrier site. The Gateway Server-Enterprise (GS-E) is located inthe various enterprise sites. GS-C supports carrier network SS7 and IPsignaling within the carrier's network environment. The GS-C may containinformation about multiple enterprises that use the present inventionincluding information about the individual enterprise networkconfigurations. The GS-C may also contain certain subscriber informationfor employees of the enterprise that assists the GS-C in optimallyrouting the calls or handle emergency situations. The GS-C communicateswith the GS-E sites to determinine if the cellular call should be routedinto the enteprise network, and if so what is the closest point ofattachment. Advantageously, the interface between the GS-C and GS-E istypically all IP-based—SIP, SIGTRAN or even an encapsulation of cellularprotocols such as GSM MAP or ANSI-41 within IP or SIP. The GS-Einterfaces with the enterprise PBX. Once the optimal routing is defined,the GS-E informs the GS-C. The GS-C communicates with the carrier'ssoftswitch and media gateway to establish a bearer path that convertsthe TDM voice from the MSC to VoIP to be delivered to the enterprise.Once the bearer is connected with the enterprise, it is redirected tothe appropriate destination using the bearer resources of theenterprise, such as VoIP connections to other offices, leased lines, orPSTN. The signaling and bearer traffic may traverse Session BorderControllers at the carrier and enterprise sites.

One preferred call flow for Call origination is shown in FIG. 6, and isas follows:

-   1. Origination Request received from Wireless Network-   2. Info message used to query GS-E about mobile origination policy    for subscriber-   3. info message received by GS-C with mobile origination policy-   4. Response is returned to ORREQ giving GS-C as the destination of    the call-   5. SS routes call to GS-C-   6. GS-C—conveys the now call initiation to the GS-E-   7. GS-E provides routing information to GS-C to get the mobile    subscriber's call to route to their home PBX-   8. Receipt of routing information is acknowledged by GS-C-   9. The call is responded to providing the new contact address for    GS-E.-   10. Rerouting response is acknowledged-   11. The call invitation is routed to GS-E-   12. Media Server ports are requested—so that digits dialed can be    capture for feature invocation-   13. The media server responds with the ports allocated.-   14. GS-E sends the call invite to the PBX for routing to the    intended destination-user B-   15. The PBX forwards on the Call invite to the User B-   16. User B indicates that ringing is occurring-   17. The PBX sends the ringing indication onto the GS-E-   18. The GS-E propagates the ringing indication to the wireless    network-   19. User B answers the call-   20. Answer is sent by PBX to GS-E-   21. GS-C provides the destination port information to the Media    Server-   22. Media Server acknowledges request-   23. GS-C sends response to call onto wireless network-   24. Answer is acknowledged by wireless network-   25. GS-C propagates the acknowledgment to the PBX-   26. PBX propagates the acknowledgment to User B-   27. User B hangs up the call-   28. PBX propagates the BYE to GS-E-   29. GS-E, releases the media Server context-   30. Media Server acknowledges the release-   31. GS-E propagates the Bye to the wireless network.

One preferred call flow for effecting Call Delivery using VoIP is shownin FIG. 7 and is as follows:

-   1. Call Originates to PBX-   2. PBX delivers call invite to User B desktop phone-   3. PBX forks the call—delivers call invite to GS for wireless user-   4. GS-E allocates a media port to insert into the call path-   5. Media Server acknowledges media resource allocation-   6. User B indicates that ringing is occurring on desktop phone-   7. Invite for mobile phone is sent into GS-C-   8. GS-C using the Location Request—asks for the Temporary Routing    number required to deliver call to endpoint-   9. Wireless network responses with the TLDN-   10. GS-C tells GS-E to redirect the call to the TLDN-   11. 302 Response is acknowledged-   12. GS-E routes the call to the TLDN-   13. Wireless network indicates that ringing is occurring on wireless    phone-   14. GS-E propagates ringing to PBX for wireless end point-   15. Wireless phone indicates that call has been answered-   16. GS-E modifies media context to include the wireless port number    information-   17. Media server acknowledge update of media context-   18. GS-E sends OK to PBX to acknowledge answer of call-   19. PBX cancel the call log to User B-   20. PBX acknowledges call answer to GS-E-   21. GS-E propagates ACK to wireless network-   22. User B acknowledges the cancel request-   23. PBX acknowledges receipt of the request terminated message.

One preferred call flow for effecting Mobile termination using VoIP isshown in FIG. 8 and is as follows:

-   1. Termination Trigger indicating that call has been terminated to    Mobile number-   2. GS-C requests termination policy from GSE-   3. GS-E returns termination policy and based on policy routes call    into enterprise for handling-   4. GS-C reroutes call into Enterprise for handling-   5. Call arrives at GS-E for handling-   6. GS-E allocates media ports for feature invocation-   7. Media Ports and allocate and response is returned-   8. GS-E ask PBX to route call to appropriate end point-   9. PBX sends invite to end point-   10. End Point starts ringing the end point-   11. Ringing indication is sent back to GS-E-   12. Endpoint answers the call-   13. Response is relayed to GS-E-   14. Media Ports are modified to reflect end point IP address/port-   15. Media Server confirms that ports have been set up-   16. Ack confirms that bearer path is set up to PBX-   17. Ack confirms to end point that bearer path is set up

TABLE 1 Benefit Description Increased personal The gateway server'scellular access enables anytime, anywhere and workgroup accessibilityusing the enterprise's corporate PBX network. Extending productivityvoice and other applications such as e-mail and instant messaging withmobility creates immediate productivity improvements Lower Long Becausethe gateway server solution includes routing Distance Costs allenterprise users' cellular calls through the enterprise Voice over IPnetwork, voice traffic is always routed efficiently and takes advantageof the enterprise's low cost long distance services. The higher volumeof traffic also enables the enterprise to negotiate better rates fromtheir long distance service provider. Seamless integration Using Voiceover IP technology, the gateway server integrates with the enterpriseseamlessly with the enterprise's existing PBX solution. Additionally,the PBX and IT gateway server provides a platform for tightlyintegrating wireless applications access with IT applications. Examplesof these applications include e-mail, instant messaging, sales forceautomation, enterprise resource planning, field support, time reporting,customer billing, etc. Control of a Mission The gateway server enablesthe enterprise to control its cellular service Critical Service bothfrom an administrative perspective and a disaster recovery perspective.For example, the gateway server lets the enterprise and/or the employeehandle the provisioning of their own services. Additionally, the gatewayserver supports geographic redundancy, such that in the event of adisaster at one location, all control is transferred to the backupinstallation. Leverages existing The gateway server solution allows theenterprise to re-use other voice enterprise and data infrastructure forboth desktop and cellular use-One key infrastructure example is theenterprise voice mail system: Both the desktop phone and wireless phonecan forward to the same voice mail box operated by the enterprise.Message waiting indicators can be turned on and off on both phonessimultaneously. Enables “best- The gateway server enables the enterpriseto monitor and record cellular practices” control phone calls, just asthey can do with deskphone calls today. This procedures supports“Sarbanes-Oxley”-like control procedures that are being implemented bymajor corporations for best practices. Seamless cellular The gatewayserver solution includes the necessary business agreements service,globally (including roaming agreements) to enable enterprise users tohave seamless cellular access all over the world. Higher Control forCompanies typically allow an employee to choose their own cellular theEnterprise phone, plan and carrier. Unlike the desktop phone, thecompany has no controls over how the employee uses the cellular phone.The gateway server solution provides for a policy-based serviceprovisioning: Employees are given a profile which defines what kind ofcalls they can make. Today, when the employee terminates theiremployment with the company, they keep their phone and cellular phonenumber. As the company's customers have been given this number, theywill continue calling the employee after he has left the company. Withthe gateway server solution this situation will not occur as the companyis now in control of both the mobile device and cellular number. Callsto an uunsed number can be intercepted and handled appropriately.Convenience of Enterprise users will no longer have to give out bothdesktop and One Number cellular numbers. The gateway server solutionintegrates seamlessly with the enterprises PBX and enables advancedservices like “One Number”. Single corporate The gateway server and theenterprise PBX can share a common dialing wide dialing plan plan. Thismeans that four or five digit dialing available on the desktop phone canalso be used on the cellular phone (both in and out of the office). Italso means that all cellular calls will be routed in the same way a calloriginated from a desktop is routed. Lower Using the gateway serversolution, the enterprise always receives the Administration lowestnegotiated rate for both cellular voice and cellular data traffic. CostsThe gateway server decides whether to route the call into the enterpriseto be routed over the enterprise network, or to instruct the cellularnetwork to proceed with routing the call (for example, if one enterpriseuser is calling another enterprise user on the same cellular network,and neither user is marked for the conversation to be monitored).Neither the enterprise nor the employee have to evaluate the differentplans the cellular operator offers and guess at which one would be bestsuited to the employee. Instead, all employees are part of the singlecorporate negotiated plan. Additionally, costs involved in expensing andreimbursing employee cellular phone costs are eliminated. Security Asthe gateway server includes the wireless data router, securityvulnerabilities are reduced as data traffic is never “exposed” outsideof the enterprise.

The invention enables a multi-dimensional paradigm change that hasprofound effects on the overall industry, as it will not only change howenterprises purchase and use cellular service—but will ultimately impactthe entire value chain for wireless and wireline service providers andmanufacturers.

The gateway server 10 architecture enables the migration of centralizedcall control from the cellular carrier networks to distributed callcontrol throughout individual enterprise networks. The gateway server 10enables cellular service to effectively be “plugged-in” to the PBX,similar to how local and long distance service are connected to currentPBXs.

As a result of gateway server 10 capability, enterprises are equippedfor carriers to compete for the enterprise's cellular PBX service asthey do today for local and long distance interconnection with the PBX.By winning the business, carriers will benefit from locking in largenumbers of users while significantly reducing its sales, marketing, andacquisition costs since service minutes will be sold bulk to theenterprise as a whole, no longer to individual employees. Though theinvention has been described with respect to a specific preferredembodiment, many variations and modifications will become apparent tothose skilled in the art upon reading the present application. It istherefore the intention that the appended claims be interpreted asbroadly as possible in view of the prior art to include all suchvariations and modifications.

Advantages of the gateway architecture are shown in Table 2.

TABLE 2 Situation without Gateway Server Situation with Gateway ServerCost for Cellular High Cost Low Cost Service Asset Reuse No utilizationof enterprise telecom High utilization of enterprise assets enterprisetelecom assets Services Purchase all services from carrier Reusecorporate Voice over IP, least (e.g. Long Distance, cost routing,voicemail, etc. Voicemail, 3-way calling, etc.) Devices Each employeerequires a deskphone Possibility to replace deskphone with and aseparate cellular phone cellular phone results in less equipment tosupport and less subscriptions Move-Add- MAC required every timeemployee No MACs required for cellular-PBX Changes changes offices fordesk phone = users (MACs) time + expense Control of Low degree ofcontrol-managed Higher degree of Control for Cellular Usage exclusivelyby carrier enterprise Rate Individual cellular subscription Bulk Ratediscount minutes for all plans employees On-Net Routing Two-stagedialing required. Difficult Automatic on-net routing, no user to dialcontacts intervention required Long Distance Purchased fromcarrier-Included in Bulk rate airtime minutes do not service plan fornational LD, charged include Long Distance (lower cost to separately forinternational at high enterprise)-any LD calls (national or ratesinternational) are routed over corporate VoIP network: “Forced on-net”Tail-end Hop No Tail-end Flop Off Tail-end Hop Off for long distance Offcalls where permitted Service Provider Individual employee relationshipsSingle relationship into Service Relationship with carrier Provider forall corporate subscribers- Better leverage for negotiating supply,reduces minutes wasted in individual buckets Sales, Carrier subject toexpenses for sales, Single relationship between enterprise Marketing.marketing, subsidies per individual & carrier: No individual sales,Customer Care, subscriber marketing, subsidies Subsidies Customer CareProvided by carrier Tier 1 provided by enterprise PBX IT department,Tier 2 by carrier Expense Manual expense handling per PBX trackscellular calls-charges to Handling employee appropriate cost center,like landline calls VolP Integration No VoIP integration-all LD fromVoIP integration with carrier carrier trunks eliminates PSTNInterconnect charges; VoIP call routing on enterprise networks for LDPolicy and No Policy control Calls subject to PBX corporate Controlpolicies per user (internal calling only, local calling allowed,national long distance allowed, international allowed) Tracking Trackingof cellular calls via printed Cellular calls automatically tracked insubscriber bill only calls PBX recorded no matter where subscriber islocated Call Cannot monitor or record Cellular calls can be monitoredand Monitoring cellular calls recorded no matter where subscriber islocated Reconciliation No reconciliation for cellular chargesReconciliation of cellular calls tracked from carrier in PBX withcarrier records Integration with Little or no integration with corporateCan be integrated with corporate IT IT Applications IT applications,applications, e.g., Corporate Phone Directory, security/badging systemsto activate/deactivate cellular phone, corporate ERP, CRM systemsConvergence Cellular, Local and Long Distance Possibility for singleprovider for from separate carriers Cellular, Local and Long DistanceOne-Number Separate desk phone and cellular Opportunity for true singlenumber service phone. for both cellular and desk phone Device Throughcarrier-no customization Direct from manufacturers. AcquisitionPossibility to standardize corporate Customization device strategy,customize to enterprise IT needs.Current Situation

Existing platforms for detecting DTMF digit events fall into one of thefollowing two categories:

Category I) Required to be a terminating end-point for a call session

Category II) Expensive hardware-based solution

Category I) solutions do not allow the call server to provide mid-callservices during an active two party call session and therefore do notprovide the necessary functionality. Category II) solutions provide thenecessary functionality but are too expensive and increase the hardwarefootprint too much to be viable solutions.

The Solution

One preferred embodiment of the invention includes a new mechanismwhereby a VoIP call server can detect Dual Tone Multi Frequency (DTMF)digit events within the bearer stream of a VoIP call session. A callserver is defined as being an intermediate node on the signaling path ofa call (e.g. a routing proxy) rather than an endpoint such as anInteractive Voice Response (IVR) system. This embodiment of theinvention allows the call server to cost effectively provide mid-callservices to end clients based on DTMF digit events originated by aclient.

This preferred embodiment of the invention, herein as the Packet Engineand shown in FIG. 12, allows a call server to detect DTMF digit eventson the call path of an active two party call session using a softwareonly solution. This software only solution provides the requisitefunctionality in a cost-effective and scalable manner.

The Packet Engine can be advantageously deployed on a separate hardwareplatform from the call server, on the same hardware platform, or evenstatically linked into the call server process itself in order toprovide both flexibility and scalability. The Packet Engine supportscontrol by multiple call servers in the network. Likewise, a single callserver can control multiple Packet Engines providing for a many-to-manyrelationship.

In one preferred embodiment, the Packet Engine consists of two parts: auser space process as shown in FIG. 13 and a Linux kernel module asshown in FIG. 14. The user space process is responsible for receivingand sending commands to/from the call server. The user space processutilizes the Linux utility IPTables to create port mappings within theIP stack. This advantageously allows RTP media packets to flow from oneside of the Packet Engine to another in a highly efficient manner (allforwarding is done within the stack preventing packets from being sentup to the user space process).

The second part of the Packet Engine, the kernel module, allows thePacket Engine to determine which packets being forwarded by the IP stackcontain DTMF digits. The kernel module examines the headers of each RTPpacket being forwarded and checks the Payload Type field. If the PayloadType field indicates the packet contains a DTMF event (encoded as perIETF RFC 2833) then the kernel module sends the packet up to the userspace process for further application level processing. The kernelmodule advantageously operates as an extension (plugin) to the Linuxkernel and therefore allows incoming packets to be examined in a highlyefficient manner since the packet never leaves the kernel.

Once in the user space, the DTMF events are reported up to the callserver in order to enable feature invocation. The Packet Engine can besupervised by the call server to only look for specific DTMF digitpatterns and report them to the call server or it can be supervised tolook for and report all DTMF digit events. The Packet Engine utilizes abuffer and an inter-digit timer to determine the start and stop of digitpatterns (e.g. *97) in order to differentiate a feature invocation digitpattern from standard DTMF digits being sent to end client applicationsuch as an IVR.

The invention also advantageously provides a network-based architecturethat enables the support for existing standard cellular handsets,without modifications or client software on the devices. Next generationspecialized Wi-Fi and client-based handsets are also supported. Bycomparison, alternative solutions may require specific expensivespecialized handsets with downloadable software clients that need to bemanaged by the enterprise IT department. The usability of these servicesis often not as intuitive and simple as using the standard phonecapability for making calls, since the software is downloaded onto thedevice and subject to the device's capabilities and restrictions such aswindow screen size and soft & hard key programming. In addition, becausethe client is itself is an application running on the device, the clienthas to be activated, or ‘turned-on’ to run the application to integratewith the enterprise network. This means it may be possible that theemployee chooses not to activate the feature, and thereby continue tomake calls on the cellular network that are not tracked, managed,monitored or routed over the corporate network (for least cost routing)by the enterprise's PBX.

Because the described solution is network-based, the employee cannotcircumvent the enterprise integration. At the discrection of theenterprise, employees may be permitted to use the cellular phone forpersonal use, for example on weekends or after work, by tracking thesecalls and charging them to the employee or deducting directly from theirpaycheck. The cost of the personal calls may still be at the corporatediscounted rates which would thereby benefit the employee.

IMS Architecture

The gateway server 10 is based on the next generation IMS (IP MultimediaSubsystem) architecture as shown in FIG. 10, and is designed to bebackward compatible with legacy cellular networks based on existingcellular protocols. This feature enables the gateway server 10 to befuture proof as operators roll out an IMS architecture over time, whilestill supporting the overwhelming majority of existing legacy networksand devices that do not support IMS.

Current competing solutions are designed using legacy networkarchitecture only, with no support for IMS. Effectively, the gatewayserver IMS solution adds modules for supporting ANSI-41/WIN andGSM-MAP/CAMEL and AIN protocols to achieve backward compatibility withlegacy networks, as shown in FIG. 11.

Legend

-   -   BSC: Base Station Controller—Component of a cellular network        that connects between the MSC and the Base Station Transceivers        that communicate with mobile devices over the air    -   CAMEL: Customised Applications for Mobile networks Enhanced        Logic-A set of GSM standards designed to allow an operator to        define services over and above standard GSM services based on        the Intelligent Network (IN) standards, and uses the CAP        protocol.    -   CAP: CAMEL Application Part—Protocol stack that provides service        control for voice & data services and IP multimedia sessions    -   CCCF: Call Continuity Control Function—Signaling function for        ensuring voice call continuity across disparate networks such as        from cellular to Wi-Fi networks    -   IM-SSF: IP Multimedia Service Switching Function—Interfaces with        CAMEL Application Servers using CAP    -   MGCF: Media gateway Control Function—Signalling controller of        Media gateways using SIP    -   MGW: Media gateway—Component of a communications network that        converts between different media types (e.g. VoIP and TDM voice)        for delivering bearer traffic.    -   MMSC: Multimedia Messaging System—A system of transmitting        various kinds of multimedia contents (e.g. images, audio &/or        video clips) over wireless networks using the Wireless        Application Protocol (WAP) protocol.    -   NeDS: Network Domain Selection—Signaling function that controls        selection of different access networks for delivering calls    -   P-CSCF: Proxy Call Session Control Function—The SIP proxy server        that is the first point of contact for a terminal with the IMS        network    -   SCP: Service Control Point—A standard component of IN        (Intelligent Networks) used to execute and control IN services    -   S-CSCF: Serving Call Session Control Function—The central IMS        SIP server of the signalling plane for controlling sessions    -   SIP: Session Initiation Protocol—A protocol developed by the        IETF for initiating, modifying, and terminating an interactive        user session that involves multimedia elements such as video,        voice, instant messaging. In November 2000, SIP was accepted as        a signaling protocol of the IMS architecture. It is one of the        leading signalling protocols for Voice over IP, along with        H.323.    -   SIP-AS: SIP Application Server—IMS element for invoking and        controlling services    -   SMSC: Short Message Service Center—Application for enabling the        transmission and reception of text messages on mobile phones    -   VM: Voicemail—Application for recording and retrieving voice        messages    -   WAP: Wireless Application Protocol (WAP)—Open standard for        Internet access from a mobile phone.    -   WIN: Wireless Intelligent Network—Signaling standard designed to        allow an operator to define services over and above standard        ANSI-41 services based on the Intelligent Network (IN) standards

The invention also advantageously provides a network-based architecturethat enables the support for existing standard cellular handsets,without modifications or client software on the devices. Next generationspecialized Wi-Fi and client-based handsets are also supported. Bycomparison, alternative solutions may require specific expensivespecialized handsets with downloadable software clients that need to bemanaged by the enterprise IT department. The usability of these servicesis often not as intuitive and simple as using the standard phonecapability for making calls, since the software is downloaded onto thedevice and subject to the device's capabilities and restrictions such aswindow screen size and soft & hard key programming. In addition, becausethe client is itself is an application running on the device, the clienthas to be activated, or ‘turned-on’ to run the application to integratewith the enterprise network. This means it may be possible that theemployee chooses not to activate the feature, and thereby continue tomake calls on the cellular network that are not tracked, managed,monitored or routed over the corporate network (for least cost routing)by the enterprise's PBX.

Because the described solution is network-based, the employee cannotcircumvent the enterprise integration. At the discrection of theenterprise, employees may be permitted to use the cellular phone forpersonal use, for example on weekends or after work, by tracking thesecalls and charging them to the employee or deducting directly from theirpaycheck. The cost of the personal calls may still be at the corporatediscounted rates which would thereby benefit the employee.

System and Method for Executing Originating Services in a TerminatingNetwork for IMS and Non-IMS Applications

The invention describes a system and method for executing originatingservices in a terminating IP Multimedia Subsystem (IMS) network in whicha triggered application may or may not support IMS.

One of the benefits of such an invention is to enable an IMS network tointerface with a non-IMS network. Another benefit is to enable an IMSnetwork to interface with a second IMS network supporting a non-IMSapplication. A third benefit is that an originating IMS network need nothave to support all originating services for the originator as theinvention enables a second network to offer originating services for anoriginator in a first network.

A Gateway Server acting as an IMS standard-compliant SIP ApplicationServer in a first IMS network can communicate with a corresponding GS inthe terminating network to enable origination services to be executed inthe terminating network even if the terminating network is notIMS-compliant. The GS-C is typically located in the wireless carriernetwork which may be IMS-compliant, while the GS-E is typically locatedin the enterprise network which may or may not be IMS-compliant. Thisapplication server in the enterprise could be a PBX which effectivelyserves subscribers in a manner similar to an IMS Serving-CSCF, howeverdoes not support IMS interfaces.

Irrespective of whether the terminating network is IMS-compliant or not,the described architecture in which a GS is acting as an IMS-compliantSIP-AS within the IMS network interfacing with a GS in another networkenables this second network to offer origination services separatelyfrom the first network.

For this to occur, the session, when passed to the GS-C applicationserver, is redirected into the terminating network, which could be anenterprise. This is performed by resetting the destination address to anenterprise specific address and instructing the wireless network routethat session into the foreign domain of the enterprise network. GS-C maycommunicate with the GS-E directly outside the IMS network, or throughthe stand IMS network messaging.

To enable the execution of originating services within the terminatingnetwork, the GS solution enables the enterprise network to provide thoseservices by passing the session to a PBX as if it were a request fororiginating services. Therefore two types of originating services can beexecuted—those in the wireless carrier network (the originating network)and those of the enterprise (the terminating network).

In a similar manner, termination services are executed in theterminating network. When a session is terminated to an enterprise user,the GS solution enables the PBX to execute its terminating services forthat user, and then pass the session to the IMS network as a terminationsuch that the terminating wireless carrier may also apply terminatingservices for the terminating mobile subscriber.

FIG. 15 outlines the current IMS standard definition in which an IMSdevice A originating a session with the carrier IMS network communicateswith the data gateway (1) which forward to the P-CSCF (2) whichultimately communicates with the Serving-CSCF (3). The S-CSCF triggerson the Initial Filter Criteria (IFC) to one or many SIP-AS which performthe origination services for user A prior to routing the session (6) tothe destination in the terminating carrier IMS network through theI-CSCF to user B's S-CSCF (7).

The S-CSCF then triggers on the IFC to one or many SIP-AS which performthe terminating services for User B (8)-(9) prior to terminating thesession through the data gateway (11) to user B.

FIG. 16 outlines the invention whereby the steps 1 through 5 are thesame as previously described, whereby the GS-C represents a SIP-AS thatis triggered by the IFC. The GS-C may communicate with the GS-E directly(8) to prepare it for an upcoming communication (9), in which case theGS-C/E are treated as a complex by the originating network's S-CSCF.Alternatively the GS-C can communicate with the GS-E entity through thestandard IMS interfaces (9). In either case, the S-CSCF then routes thesession (9) to the destination in the terminating carrier IMS networkthrough the I-CSCF as part of the GS-E, to user B's S-CSCF (10), whichmay act as a front-end converted to a non-IMS application such as a PBX.In this case the S-CSCF Front End (FE) converts the IMS messaging intothe corresponding SIP-AS service-invocation messages of the non-IMSapplication (11).

The FE may convert the terminating services request to an originatingservices request prior to communicating with the terminating service(11). This allows the terminating service to invoke services as if itwere an originating node. For example, the PBX can perform originatingservices such as invoking call policy (restrict user A from dialinginternational) prior to routing the call.

Once the originating services are executed, the non-IMS application canthen perform terminating services. For example, the PBX could invokedestination services for user B to route calls from user A to voicemail.

In the case where the terminating network application were IMS-compliant(e.g. an IMS-compliant PBX), the FE would convert the terminatingservices request to an originating services request prior tocommunicating with the IMS-compliant application (11), and once theoriginating service has been performed, the application would returncontrol to the FE which would then invoke another service request backto the IMS-compliant application to perform terminating services.

System and Method for Enabling Multi-Line Mobile Telephone Service on aSingle-Line Mobile Telephone

Another embodiment of the invention includes a system and method forenabling a multi-line mobile telephone service using a single-linemobile telephone. The embodiment of invention applies to various networkarchitectures used in communications systems including legacy mobilenetwork architecture based on SS7, GSM-MAP and/or ANSI-41, as well asthe next generation IP Multimedia Subsystem (IMS) network architecture.

One of the benefits of this embodiment is enabling a subscriber tomanipulate the outgoing caller identification information whenoriginating a call, such that the called party will see the identity(including the phone number and name information) that was selected bythe calling party.

An example of this embodiment of the usage of the invention might be adoctor whose patients are directed to call a special phone number toreach the doctor after hours. The doctor can set the special after-hoursphone number to forward to their mobile phone using existing solutionsthat exist today. This way the doctor need not give out their personalmobile phone information. When a patient calls the special after-hoursphone number, the call is forwarded to the doctor's mobile phone withoutrevealing the doctor's mobile phone number to the patient.

However in the reverse case, this embodiment of the invention enablesthe doctor to call a patient from their mobile phone without revealingtheir mobile phone number. This is done by enabling the doctor to selecta specific outgoing line from which to originate the call on theirmobile phone. The patient will see the calling party identificationinformation of the outgoing line selected by the doctor, which could bethe special after-hours phone number, not be the doctor's mobile phonenumber.

The function of this embodiment of the invention is described below.This feature can operate in a legacy mobile network architecture such asGSM-MAP or ANSI-41, or in a next generation architecture such as IMS.

Outgoing Call Handling

Prior to originating an outgoing call the calling party can identify theoutgoing line information using various means such as:

-   -   On a per-call basis, dialing a prefix to the outgoing number        such as #542 or *542 (where 54 are the digits that represent the        letters LI on a telephone keypad) indicating to use Line 2. Thus        the digit string might be *542-212-481-2813<SEND>    -   On a permanent calling basis, dialing a feature-activation code        such as #542 or *542 indicating to use Line 2 for all outgoing        calls until a subsequent instruction is received. The digit        string might be *542<SEND>. The subscriber can then dial any        outgoing call such as 212-481-2813, and the call will be        originated from Line 2.

Referring to FIG. 17 and FIG. 18, to enable this capability, a GatewayServer Carrier (GS-C) acting as an IMS standard-compliant SIPApplication Server in an IMS network architecture, or acting as an SCP(Service Control Point) in a legacy network architecture, will betriggered by the network to invoke a service. In the IMS case thistrigger typically results from the Initial Filter Criteria (IFC) that isderived from the subscriber's Home Subscriber Server (HSS) profile andutilized by the Call State Control Function (CSCF). In the legacy casethis trigger results from an intelligent network trigger that isoriginated from the Mobile Switching Center (MSC) based on thesubscriber's Home Location Register (HLR) profile.

Once the trigger is received in the GS-C containing the digits dialed bythe subscriber, the GS-C can then invoke the service whereby it cancommunicate with a Gateway Server Enterprise (GS-E) located in anenterprise. The GS-E can then originate an outgoing call to the intendeddestination using the outgoing line including the appropriate callingline information selected by the subscriber, and then connect thatoutgoing call leg to the originating call leg from the subscriber.

In the case of a per-call invocation of the multi-line service,subsequent calls made from the mobile phone would have the lineselection default back to either a primary line, or to the last lineselected in a previous call. For example, if a user's primary line is212-814-4490, and they originate a call with digits *542-212-481-2813indicating to use line 2 to call to destination 212-481-2813, then ifthe same subscriber subsequently dials another number such as212-777-2222, this call would originate from either the primary line212-814-4490 or from the previously selected line 2 from the previousper-call invocation of *542-212-481-2813. Thus the called party(212-777-2222) would see the calling party information as either theprimary line 212-814-4490, or the previously per-call selected line212-481-2813. The preference of whether subsequent calls should defaultback to the primary line or to the last line selected in a previous callcan be defined by either the service provider, the system administratoror the user if permitted.

In the case of a permanent invocation of the multi-line service, allsubsequent calls to the feature invocation (i.e. following the dialingof *542 indicating the selection of line 2), would continue to use line2 until changed by the user, the system administrator or a function suchas a timer or external application. For example, a calendar event couldautomatically reset a doctor's outgoing mobile phone line back to thedaytime office number beginning each morning.

Additionally, a user may select a personality or profile based onvarious criteria (such as the user being at work, in a meeting, at homeoutside of work hours, etc.). The personality or profile can be selectedmanually or automatically set based on criteria such as whether theemployee has badged into the office or has logged into their workcomputer, Time-of-Day or Day-of-Week information, or other criteria. Thepersonality or profile would determine the outgoing line to be used—suchas a personal line when after six in the evening, or when the user hasbadged out of the office or has logged out of their work computer.Additionally the personality or profile could determine which voicemailsystem to use, in addition to the customizing and tailoring of otherservices.

Incoming Call Handling

Referring now to FIG. 19, for incoming calls on various lines that areto be directed to the subscriber's mobile phone, the calling name andnumber information may be preceded with supplementary information toindicate which line was called. For example, an indicator such as 2#could precede the incoming calling name or calling number information toindicate the call came in on line 2. Simultaneously or alternatively adistinctive ring can be invoked instead of the standard ring, toindicate which line was dialed by the calling party.

Note in some cases replacing the first set of digits (such as the areacode digits) with the line information may be preferred instead ofprefixing the line information to the full digits in order to preservethe display formatting on certain mobile phones. This is because certainmobile phones support only ten digits in the display, therefore if lineinformation is prefixed to the digits, the ending digits would notappear in the display.

Incoming calls on various lines that are intended to be routed to thesubscriber's mobile phone terminate at the GS-E. The GS-E identifies thedestination mobile phone to which the incoming call should be routedbased on various criteria such as time-of-day, day-of-week, permanentsettings, or other user/administrator settings for determining callrouting.

If the GS-C has the ability to originate outgoing calls then the GS-Eorders the GS-C to originate a call to the subscriber's mobile phonewith the calling name and number information of the calling partyprefixed with supplementary information to indicate which line wascalled, and/or with a distinctive ring indicator. Once the outgoing legis established, the GS-C connects the outgoing leg to the incoming callleg in the control of the GS-E.

If the GS-C does not have the ability to originate calls then the GS-Eoriginates the outgoing call to the subscriber's mobile phone with thecalling name and number information of the calling party prefixed withsupplementary information to indicate which line was called, and/or witha distinctive ring indicator. Once the outgoing leg is established, theGS-E connects the outgoing leg to the incoming call leg.

TECHNICAL ADVANTAGES

1. Provisioning: The gateway server may also support a provisioningengine for provisioning the functions of the server itself, as well asprovisioning external nodes including the enterprise PBX and the publiccarrier cellular network nodes. It may be possible that the gatewayserver provisioning engine (GSPE) front-end the entire PBX and be usedto provision all data in the PBX. Alternatively the GSPE may be used toprovision all functions in the PBX related to a cellular subscriberincluding their landline information, or it may be used to provisiononly the cellular portion of PBX subscriber information. In the cellularnetwork, the GSPE may be used to provision the HLR/HSS of the carrier tomodify existing service profiles for employees that are currentlysubscribers of the operator's network and are being transferred to thenew service plan for enabling this service. The GSPE may also be usedfor provisioning new subscribers to the service that were previously notsubscribers of that operator. The GSPE may also be used for provisioningother nodes in the cellular network such as a Foreign Agent, Home Agent,soft-switch, MSC, SGSN or GGSN. These functions would typically beprovisioned with routing information used for enabling the service.

2. Method for speeding up call originations/terminations by usingpredictive techniques for routing half call, using intelligence todecide when to route calls to different devices based on presence,routes, TOD, distance. Calls routed to/from a subscriber of this servicetypically occurs in two stages, e.g. from the cellular network to theenterprise, and from the enterprise to the destination. Since thegateway server is notified in the first stage of the originator and thedesired destination, it is possible for the GS to begin routing thesecond leg prior to the first leg's bearer being established. Usingintelligence of the destination route combined with knowledge from pastexperience in the time it may take to route to a certain destinationusing a particular method or link, the GS may predict the moment atwhich it should begin routing the second leg of the call in anticipationof receiving the indication that the bearer for the first leg beingestablished such that the two legs can be connected together with nodelays. This technique can be used to minimize the chances that thesecond leg will be established and answered by the destination partybefore the first leg is setup. Conversely, this technique may minimizethe wait of the originating party for the second leg to be establishedsince the first leg need not be completely established to the enterprisebefore routing of the second leg is started. The GS may continuouslyupdate its information with intelligence about the routing times forspecific destinations, and use this information in deciding the timingof setting up the call legs in order to minimize the end-to-end callestablishment time.

3. Enterprise Call presence for mobile phones: Because the GS is locatedin the call path, the GS maintains knowledge of when a subscriber isactive and available for calls, and also when a subscriber is currentlyin an active call. The GS can share this information with applicationsthat may be used to, for example, indicate to other users that thesubscriber is currently busy in a call. When the subscriber terminatesthe call, this information can be used to inform another user that thesubscriber is available to receive a call. This presence information canalso be provided to other presence servers that may be outside theenterprise site including with the carrier.

4. Enterprise HLR/HSS: The invention enables the distribution of HLR/HSSsubscriber information among multiple sites within the enterprise. Forexample, the HLR/HSS information may be distributed according to thevarious PBXs in the enterprise network such that cellular information isstored at the site where the subscriber has a PBX subscription. Thelocation of this information within the enterprise can be hidden from anoutside entity such as the public carrier network such that an outsideentity need not have to know where it is stored in order to access it.Any point of entry to the enterprise network may be able to locate theinformation of a particular subscriber.

5. Data—VPN-less session setup for enterprise. The invention enables aGGSN or HA to be including in the GS in the enterprise such that asecure data session can be established automatically between a device onthe cellular network and the enterprise network by establishing a GTPtunnel between the carrier-hosted SGSN and the enterprise-hosted GGSN.In addition, in the case where there is a GS-C located in the carriernetwork that interfaces with GS-Es in the enterprise network, it ispossible for the invention to add additional security and encryptionspecific to the enterprise's needs between the carrier's network and theenterprise. In this configuration, the function of the GGSN can be splitbetween the GS-C and the GS-E such that the carrier network interfaceswith the GS-C hosted within the carrier site, while the GTP tunnel andsecure encrypted data session can be drawn out to the GS-E hosted withinthe enterprise. All data traffic to/from the mobile device will traversethe enterprise and its associated secure firewall. Billing for thewireless carrier can be supported within the carrier's network viacharging records being generated from the GS-C. Enterprise chargingrecords can equally be generated within the enterprise from the GS-E inorder to enable the enterprise to keep track of usage and be able tocompare with service bills from the carrier received at the end of abilling cycle.

6. Alternative methods for handling call originations: Using SMS andHotline for call originations: Alternative solutions can be used inplace of Intelligent Network triggers such as WIN or CAMEL forcommunicating with an SCP function in the enterprise. One technique isto use a method such as Short Message Service (SMS) to send theorigination information from a mobile to an application server in theenterprise, and then to enable a “hotline” feature in the subscriberprofile that forces the mobile to route to a specified destination nomatter what is dialed. The hotline feature is often used to route tocustomer service when a new phone is being setup. In this case thehotline feature would route all calls to a destination that wouldultimately route into the enterprise network, either using VoIP or PSTN.By sending the origination information including the originatingsubscriber number and the destination digits to the application serverin advance of the hotline call, this information can be used to identifythe incoming hotline call, and re-route it to the desired destination.In order to be able to use SMS in this manner, it may be required tohave a special client on the device that captures the digits and sendsthem in an SMS to a specific server. Alternatively this functionalitycould be built into the device natively thus not requiring a softwareclient. Note in this case that the destination SMSC may also be the GSinstead of the carrier's SMSC since it is important that thisinformation be delivered in real time, and not delayed throughstore-and-forward in the carrier's SMSC. Otherwise the routing of thecall could be delayed. An alternative routing method does not requirethe hotline feature to be activated. Instead, when the SMS message isreceived at the application server, the application server can originatecalls to the destination and to the originator's device. The originatorwould answer the phone and be connected with the second leg. If a clientis on the device, the client may automatically answer the incoming callfrom the application server without ringing so as to appear as if thecall was established by the originator's device when the SMS was sent.Other methods other than SMS for delivering the origination message maybe used such as over-the-air messages and/or Unstructured SupplementaryService Data (USSD). Another alternative provides that originating callsare routed based on the subscriber profile to specific routes or trunkgroups within the MSC. The destination routes to the GS which capturesthe original calling and called party information. The GS can analyzethe routes and re-route the call accordingly, for example into theenterprise using VoIP. This solution also enables the GS to manipulatecall legs to be able to perform handovers (or handoffs) between, forexample, a wi-fi network and a cellular network by enabling the GS toestablish a new call leg for a call in progress and join or switch thefailing call leg to the new leg. Similarly this kind of call legmanipulation can be used to maintain or reconnect a call that has beenlost—for example if a subscriber enters a tunnel where there is nocellular coverage and therefore the call leg is lost, the GS can decideto maintain the other call leg up and potentially treat the leg byplaying a message to inform the party that the call is beingreconnected. The GS can then proceed to re-establish the call leg byestablishing an outbound call to the device once they exit the tunnel,or having the device originate a call back to the GS if the device has asoftware client—and then the GS can reconnect the legs together, or theuser manually originates a call back to the GS.

7. The combining of cellular nodal functions in a single functionalentity: GMSC, GGSN, SCP, IMS SIP Application Server, Call Server. Theinvention combines the functionality of multiple cellular network nodesinto a single entity that is scaled down to support in the order ofthousands of subscribers compared with individual cellular nodessupporting millions of subscribers. The invention supports a GMSC forenabling call originations to an enterprise number to be redirected to acellular phone number and routed using least cost routing techniqueswhereby the GS discovers the location of the terminating subscriber andcan route the call to that serving MSC over alternate routes such as apublic or private VoIP network. This reduces or eliminates transportcosts to the public carrier since the call is routed over lower costroutes using VoIP, or completely outside the carrier's network. Theinterconnection to the carrier's network can be using VoIP which avoidsany PSTN interconnect charges. The SCP function enables originating andterminating calls to be routed according to instructions from theenterprise in the GS which interacts with the enterprise PBX system.Similarly this is achieved with the IMS SIP Application server functionin the case of an IMS network architecture. The Call Server enables thecarrier to route calls to and from their network using a distributedsoft-switch and media gateway architecture that enables the bearer to betransmitted over VoIP instead of traditional trunks. Thus the carriercan route calls into and out of the enterprise over VoIP therebyavoiding PSTN interconnection and associated charges. The GGSN functiononboard the GS enables the enterprise to route data sessions in asimilar manner to how the invention describes the routing of voicecalls. By including a GGSN function within the enterprise and connectedwith the cellular carrier's SGSN, a secure tunnel can be establishedbetween the carrier and the enterprise networks. Similarly this can beachieved with a Home Agent function located within the enterprise andconnected with the carrier's Foreign Agent for CDMA networks. As such,the invention:

-   -   i. Eliminates the need for VPN software to be launched on the        mobile device    -   ii. Subjects the mobile device to enterprise data policy        including security and firewalls no matter where the device is        located, and without the need for user interaction—all data        sessions are routed through the enterprise's corporate network        and firewalls    -   iii. Enables software applications to be embedded in wireless        devices that can be launched remotely to, for example, destroy        data on the device should the unit be lost or stolen—e.g. Poison        Pills

8. Least cost routing for mobile originations to bypass long distance incontrol of enterprise: The invention describes how to bypass longdistance for cellular subscribers for both international and nationallong distance, by routing the calls from the serving MSC into theclosest point of entry into the enterprise network. This connection canbe using traditional trunks which incur costs but is reduced since thecall may be routed from the serving MSC to a local point of attachmentto the enterprise network, or the connection can be using VoIP from thecarrier network to the enterprise, which avoids any PSTN interconnectcharges and also enables the call to be considered a local call even ifthe closest point of attachment is not local—the cost is according toVoIP tariffing which may include free nationwide as well as to Canada,western Europe and parts of Latin America. The invention also describesthe concept of Tail-End-Hop-Off (TEHO). TEHO enables an employee dialinglong distance to route the call as far as possible via least costrouting, and route the last leg from the least expensive point. Forexample, if an employee in the US dials a local telephone number inLondon, UK, the GS could detect this and decide to route the call fromthe US to the corporation's office in London, and from there initiate alocal call to the destination. The invention would then enable all thelegs of the call to be connected together. The end-to-end call would berouted from the originator in the cellular network into the enterprisenetwork via a local connection, across the corporation's least costrouting (possibly VoIP) network to the London office, and connected withthe local call from the London office to the final destination. Theinvention also stipulates that TEHO could be disallowed based on variouscriteria, such as destination (e.g. if such a solution were not allowedfor connecting to certain countries), Time of Day/Day of Week or othercriteria such as subscriber profile or policies.

9. PBX feature transparency: The invention describes how to enable PBXservices from a desk phone be executed on a standard cellular phone withno special clients. The GS is configurable specific to the enterprise.Therefore the feature codes used on a deskphone in a particularenterprise can be programmed to be the same or similar on the cellularphone. The GS enables the use of “7” or “9” to be dialed in order to getan outside line, just like on a PBX. On the cellular phone, the employeewould dial 9 followed by the destination digits, followed by the TALKbutton. If the employee dials destination digits without a “7” or “9”,the GS would consider them as internal PBX digits, such as a local 4 or5-digit extension, or a 7-digit internal network destination. It ispossible for the GS to suppress the use of “7” or “9” when using acellular phone. The GS would analyze if the digits are internal orexternal and route accordingly. For example if the user dialed only 4digits, the GS would treat as an internal extension. If the user dialed10 digits, the GS would analyze the digits and if not associated with aninternal extension, would consider it an external call and add the “7”or “9” prior to routing to the PBX. By enabling the suppression of the“7” or “9” for an outside line, the invention enables the employee touse the phone numbers stored in their device as they are—withoutmodification. An employee can select a person's name and which numberthey wish to connect with (office, home, cellular) in their directory inthe phone and dial, and the GS will determine automatically if it is anexternal or internal number, and route accordingly. Advanced PBXfeatures such as Call Forward, Call Park, Call Pickup, Conference,Transfer, Do Not Disturb, Exclusive Hold, Consultative Hold, Last NumberRedial, Link, Page, etc. that are available on the deskphone by pressinga “Feature” button followed by a code (e.g. Feature 74 to invoke CallPark, or Feature 85 to invoke Do Not Disturb), can be executed in asimilar manner on the cellular phone by pressing an alternative buttonto “Feature” such as “*” or “#” followed by the same feature code. Thisis completely configurable and can be changed to suit the desire of theend user. If the user cannot recall what codes to use, the inventiondescribes that the user can press a code such as “**”, “##” or “4HELP”(44357) which would connect the user with an Interactive Voice ResponseSystem (IVR). The IVR would prompt the user with information such as“Press *74 for Call Park, Press *85 for Do Not Disturb”. The user couldenter the digits at anytime and the feature would be invoked. If theuser remembers the code, they can avoid using the IVR on subsequentfeature invocations. The invention describes the invocation of featuresat the beginning of a call, and during a call. Mid-call triggers can beused by the system to inform the GS. For example if a user wishes tobridge in a third party, they could press TALK followed by thedestination digits followed by TALK. A cellular system supportingmid-call triggers would send this information to the GS which wouldoriginate a call to the third party from the PBX, bridge the third partat the PBX, and enable the single voice path back to the cellularswitch. The GS would respond to the midcall trigger with a messageindicating to continue the call as normal. The result is that theoriginal two parties would be connected with the third party through thePBX, and not through the cellular MSC—only a single voice pathconnection from the cellular MSC is required back to the PBX. Using thesame concept, it is possible to link in multiple parties into a largeconference call using the PBX and conference bridges in the enterprise,and only a single voice path connection to the cellular user. If thecellular system does not support mid-call triggers, DTMF tones can becollected on the voice path using a code receiver placed in the voicepath typically onboard a media gateway or subscribing to a media gatewayfor tone detection service. If a code receiver is used, it could belocated in the enterprise, or at the carrier. As such, the user wouldnot press the TALK button. Instead they would invoke features while in acall by pressing a designated code such as “*”, “#”, or alternatively“**” or “##” to invoke the IVR system to assist the user in invoking theservices.

10. Monitoring and controlling of calls (voice and data) from enterprisemobiles. The invention previously described how all voice calls and datasessions from the cellular network are routed through the enterprise,enabling the enterprise to control, manage, subject to policy and evenrecord the bearer information. The implications of this invention areconsistent with what are considered “best practices” among corporationsthat must comply with regulations such as Sarbanes-Oxley for controlprocedures, similar to how corporations manage and control e-mailtraffic or PBX voice communications that can be tracked and recorded.While the invention enables an enterprise to gain control of voice anddata calls, the design of invention also continues to enable federallegal requirements for monitoring calls on public cellular networks incompliance with regulations such as CALEA. Because the invention routesall calls through the serving MSC before they are routed to theenterprise, the serving MSC can still invoke wiretapping in accordancewith federal law. Similarly the invention design fully supportsemergency call handling in that a subscriber that dials 911 will havethe call immediately routed in accordance with emergency call handingprocedures via the serving MSC which will override any triggers to routethe call to the enterprise. As the invention uses standard cellularhandsets, there E-911 location features operate as designed. Thus thearchitecture of the invention fully complies with emergency callhandling regulations.

11. Identity manipulation for outgoing and incoming calls: The inventionenables either the enterprise PBX landline phone number or the cellularphone number to be used as the single number. If the landline is used asprimary and if the cellular number is called, the call can be allowed,or the call can be diverted to a voice recording that states thelandline number to call. The call can then be routed, or it can hang upand require the originator to re-dial the new digits. Similarly this canbe done with the cellular number as primary. If the landline is primaryand the user originates a call from their cellular phone, the GS canmanipulate the outgoing callerid information to be the landline numberinstead of the cellular number. If the terminator decides to call backthe originator, they can select the callerid which will be the landlinenumber. Similarly this can be done with the cellular number as theprimary. SMS message originations from the mobile user are triggered tothe GS which converts the originator's cellular phone number to thelandline number. The SMS can then be redirected back to the MSC forsending to the SMSC, or the GS can instruct the MSC to cancel themessage, after which the GS originates a new SMS directly to the SMSCcontaining the landline origination number and the original destination.Similarly when an SMS is sent to a subscriber using their landlinenumber, the MSC will trigger to the GS based on the terminating number.The GS will convert the destination number from the landline to thecellular number and return it to the MSC for routing to the subscriberor SMSC. In this case it may be required that the HLR be provisionedwith a subscriber profile for the landline number to trigger to the GS.In the case where the GS also contains an SMSC on the SS7 network, theoriginating MSC would route the SMS to the GS-SMSC which would in turnconvert the landline number to the cellular number and originate a newSMS to the cellular network for termination.

12. Enhanced services

-   -   a. Notification of policy enforcements: The invention describes        new control procedures for mobile devices based on policies from        the enterprise. For example, the enterprise can restrict        incoming and/or outgoing calls when an employee is outside work        hours, is outside the building, has badged out of the facility        and/or has logged out of their enterprise data network from        their computer. Should the employee attempt to originate a call,        the system can provide a dynamic treatment that might play a        message to inform the employee of the policy that is preventing        the call from proceeding. Similarly, it is possible for an        incoming call to apply a dynamic treatment that might inform the        calling party that the called party is no longer in the office,        has badged out for the evening and/or has logged out of their        enterprise data network from their computer. The call could then        be routed to standard voicemail or other appropriate treatments.    -   b. Using an Application Programming Interface (API) and/or        Software Development Kit (SDK) on the GS, applications can be        written to control voice calls and data sessions. For example, a        time clock, badging system, or signaling from a computer        login/logout can be used to activate/deactivate a mobile phone.        Similarly this technique can be used to change the recording of        calls to be from a corporate account to a personal account for        charging purposes. For example when an employee logs off their        computer, the cellular phone account is switched to a personal        account and phone calls may be deducted from the employee's        paycheck. In another example, the API/SDK can be used to assign        a particular cellular phone to a particular user at a particular        time. For example, an employee may be assigned a set of        equipment at the start of a shift which might include a cellular        phone. To activate the assigned cellular phone to the employee,        the API/SDK can be used to associate the phone with the        employee. The phone may contain the same cellular phone number,        but the enterprise landline number would be assigned to route to        that particular cellular number for a duration of time until the        employee returns the device at the end of the shift.

13. Billing

-   -   a. Enabling carrier to store a enterprise-specific billing ID in        CDR: The invention describes the assigning of a billing        identifier generated by either the GS or the cellular system        that is shared between the GS and cellular network, and can be        included in the Charging Data Records. The billing identifier        can be used to correlate multiple generated CDRs associated with        a common event.    -   b. Use of Prepaid triggers to mark the start and end of calls:        The invention describes the use of cellular Prepaid triggers to        mark the start and end of calls, even if the call is routed        entirely by the cellular network. For example if user A calls        user B and the GS determines that both users are on the same        cellular carrier, and do not need to be monitored, then the GS        may instruct the MSC to proceed with routing the call from A        to B. The start and end of the call can still be recorded by the        GS based on prepaid triggers.

14. IMS-Legacy Interaction

-   -   a. Policy: The invention enables the enterprise GS to apply        policy rules to the carrier PDF in order to enable target        service objectives for the subscriber for the portion of the        service that is handled by the carrier network. Conversely the        invention enables the carrier PDF to provide the GS with policy        rules for the portion of the service that is handled by the        enterprise network. If the enterprise is not capable of meeting        the minimum policy requirements for the session, the carrier        network may take alternative actions—e.g. route the call        themselves, reject call, redirect to another service or gateway.    -   b. IM-SSF: The invention enables the IM-SSF function to be        expanded beyond CAMEL prepaid triggering to support legacy        network interaction for establishing legacy services such as SMS        and voice calls. For voice services, the IM-SSF can be used by a        SIP-AS to signal to an MSC or HLR by converting SIP messages        into, for example, ISUP, AIN, GSM MAP or CAMEL, and/or ANSI-41        or WIN. This could be used to execute a handoff procedure        between an IP network such as VoIP with a cellular network (or        vv), or to enable IMS applications to invoke legacy services        such as a voice call to a device that does not have an IMS        client and does not support VoIP.    -   c. CSCF: In the case that a solution supports Wi-Fi for voice        calls, the GS acts as a local P-CSCF in the enterprise that        interconnects with the carrier I-CSCF and S-CSCF. The GS can        also perform the functions of an I-CSCF as a peer to the carrier        network for routing sessions within the enterprise, and an        S-CSCF to service the device within the enterprise network. For        the routing of emergency calls, the GS can manage whether the        call is sent to the landline network, in which case it would        provide landline emergency location information, or to the        cellular network in which case cellular emergency call handling        would be performed including location tracking. Additionally, if        the device is in the enterprise and operating on the Wi-Fi        network, the GS could alternatively perform cellular emergency        call handling and act as a proxy for the device in order to be        able to interact with the cellular network emergency call        handling functionality. In this case the GS would support the        location information transactions with the cellular network by        providing location information of the enterprise to the cellular        network. This could be statically stored information in the GS        describing the general location of the enterprise, or specific        areas within the enterprise—or could be dynamically obtained by        the GS using various location techniques, for example based on        Wi-Fi location such as AP connection, and converted to        cellular-recognized location information. In this manner the        cellular network would require no changes, while the device        could be operating on an alternative network and still receive        emergency service.

15. Configurations: The solution enables various configurations to bedeployed.

-   -   a. Pure enterprise call control in which the GS is located at        the enterprise site. The GS interfaces with the cellular network        nodes supporting SS7 and SIP or other messaging with the carrier        network. The carrier network must be able to address the GS in        order to send and receive messages.    -   b. Split call control between carrier and enterprise in which        the GS located at the enterprise interacts with a GS at the        carrier. The connection between the GS-E and the GS-C can be SIP        or other protocols. This configuration typically enables the        carrier network to have a central point of control for        interacting with multiple enterprises, and may not require the        use of SS7 messaging to the enterprise—instead it is possible to        have a secure IP connection supporting SIP. This is also useful        for offering a Centrex solution for interconnecting with a        carrier-hosted PBX, or for interconnecting a carrier-hosted GS        with enterprise-hosted PBX systems. The GS-C supports an SS7        point code multiplexer in which only one or two point codes are        needed to address all enterprises, since the GS-C can identify        for which enterprise the message is intended. The GS-E is able        to provision the GS-C automatically over the IP interface to        manage subscribers, e.g. to add new pilot DNs for new        subscribers. In this case the triggers used by the originating        and terminating triggers used in the cellular network for        routing the calls to the GS-C can add identifying information of        the specific enterprise in the triggering messages (e.g. ORREQ).        Alternatively the GS-C can identify the enterprise based on the        calling party information.

16. Availability: PBX systems are by nature designed to beenterprise-grade, which implies they may go out of service morefrequently than carrier systems which must comply with strict minimumdowntime requirements. The architecture of the invention increases theeffective availability of a PBX system for routing calls since the GS(GS-E or GS-C) can instruct the cellular network to route the call (withsame or modified dialing instructions) in the event that the PBX hasgone out of service. The GS can store the call information and report itto the PBX when it is back online. In the event that the GS should goout of service, the architecture of the invention enables the cellularnetwork to be configured such that if its communication with the GStimes out, the cellular network can take alternate action, for exampleto route the call on its own, send to treatment (e.g. play a message),redirect to an alternative GS, or other call handling.

17. MVNO infrastructure: The invention is effectively a wireless corenetwork that could alternatively be packaged and sold to MVNOs to enablethem to operate their own core networks and host their own advancedservices, while connecting to public cellular carrier networks for radioaccess.

18. Call Leg Manipulation and handling—In addition to using originatingand terminating triggers to transfer call control from the carriernetwork to the enterprise via the GS, the solution also enables advancedservices to be executed mid-call using mid-call triggers or in-line codereceivers. When a user wishes to invoke a mid-call service such toinvoke a multi-party call using an external conference bridge thatresides in the enterprise network, the user can press digits on thedevice to invoke the service, and then press the TALK or SEND button toinvoke a flash. The flash message is sent to the GS using mid-calltriggers with the information of what was dialed. The GS can thenrespond to proceed with the call as normal, so that the voiceconversation can continue, and then the GS can invoke the service, inthis case to bridge in other users to the call, from the enterpriseside. Thus for a multi-party call, only one voice leg is required fromthe user to the enterprise. Alternatively to the use of mid-calltriggers, the solution can use an code receiver in the line thatcaptures DTMF tones throughout the call. In this case the user couldpress a series of digits followed by, for example, # (instead of TALK orSEND). The code receiver or media gateway can then send a message to theGS to perform the service. In this case there is no interruption in thevoice session. In this case the media gateway can block the transmissionof the tones to other parties on the call such that the other partieswill not hear them as they are being pressed. This section is inaddition to what is described in section “Alternative methods forhandling call originations”.

19. Corporate Calling Name: Calling name display is based on the carriernetwork database. This information does not contain calling nameinformation for internal enterprise numbers. The invention enables theredirection of the GR-1188 or IS41 based query in the terminating switchto point to the GS. The GS will access the calling name information fromthe corporate directory. The GS can also obtain calling name informationfrom a carrier database or other source, and decide which information(or both) to provide to the terminator depending on various factors suchas completeness, originator's preferences, etc.

20. IMS Handover/Handoff: The invention enables handoff to occur betweena voice conversation on a Wi-Fi network and a cellular network.Signaling between the Wi-Fi network and the cellular network istransited through the GS which converts the messaging between SIP callleg manipulation and ANSI-41 or GSM cellular signaling protocols forinvoking a handoff. The solution can support the equivalent of aninter-MSC handoff as is done today in the cellular network, oralternatively a Call Redirection pseudo handoff in which athrough-connected call is redirected. The latter uses messages such asSIP JOIN to connect the calls. In the case where the cellular networksupports IMS, the GS acts as a SIP AS to perform the applicationfunction, and can also act as a peer IMS network including P-CSCF,I-CSCF and S-CSCF. In this case, the GS acting in these functionsenables the PBX or IP-PBX that is controlling the user in Wi-Fi mode tobe abstracted from having to support IMS to the cellular network, as thePBX/IP-PBX interfaces with the GS which interfaces with the IMS network.

Data—VPN-less session setup for enterprise. The invention enables a GGSNor HA to be including in the GS in the enterprise such that a securedata session can be established automatically between a device on thecellular network and the enterprise network by establishing a GTP tunnelbetween the carrier-hosted SGSN and the enterprise-hosted GGSN. Inaddition, in the case where there is a GS-C located in the carriernetwork that interfaces with GS-Es in the enterprise network, it ispossible for the invention to add additional security and encryptionspecific to the enterprise's needs between the carrier's network and theenterprise. In this configuration, the function of the GGSN can be splitbetween the GS-C and the GS-E such that the carrier network interfaceswith the GS-C hosted within the carrier site, while the GTP tunnel andsecure encrypted data session can be drawn out to the GS-E hosted withinthe enterprise. All data traffic to/from the mobile device will traversethe enterprise and its associated secure firewall.

What is claimed is:
 1. A method, comprising: receiving, at a privatebranch exchange (PBX), an instruction to route a call to a phoneassociated with a mobile station; routing, by the PBX, the call to thephone and to an enterprise gateway server; routing, by the enterprisegateway server, the call to a carrier network; notifying, by theenterprise gateway server, the private branch exchange that the mobilestation is ringing; and cancelling, by the private branch exchange, thecall to the phone responsive to receiving an indication that the callwas answered at the mobile station.
 2. The method of claim 1, furthercomprising: transmitting, by the private branch exchange, a first callinvite message to the enterprise gateway server; transmitting, by theprivate branch exchange, a second call invite message to the phone;forwarding, by the enterprise gateway server, the first call invitemessage to a carrier gateway server; and establishing a secure tunnelbetween the enterprise gateway server and the carrier gateway server. 3.The method of claim 2, further comprising performing, by the carriergateway server, a location request.
 4. The method of claim 3, furthercomprising receiving, by the enterprise gateway server, a temporaryrouting number required to deliver the call to the mobile station. 5.The method of claim 2, further comprising forwarding, by the carriergateway server, a temporary routing number to the enterprise gatewayserver.
 6. The method of claim 2, further comprising cancelling, by theprivate branch exchange, a call leg associated with the second callinvite message to the phone.
 7. The method of claim 2, furthercomprising receiving, by the carrier gateway server, a terminationtrigger indicating that the call has been terminated to a mobile numberof a second mobile station of an enterprise network member.
 8. Themethod of claim 7, further comprising: issuing, by the carrier gatewayserver, a request to the enterprise gateway server for a terminationpolicy; and receiving, by the carrier gateway server, the terminationpolicy.
 9. The method of claim 8, further comprising rerouting, by thecarrier gateway server, the call into an enterprise network for callhandling.
 10. The method of claim 1, further comprising receiving, bythe private branch exchange, a call origination request of the calldestined to a member having the mobile station and the phonecommunicably coupled to the private branch exchange.
 11. The method ofclaim 1, further comprising receiving, by the enterprise gateway server,an indication that the mobile station is ringing.
 12. The method ofclaim 1, further comprising inserting, by the enterprise gateway server,a media port into a call path allocated for the call, and allocating, bythe enterprise gateway server, the media port for insertion into thecall path.
 13. The method of claim 1, further comprising receiving, bythe enterprise gateway server, an indication that the call has beenanswered at the mobile station.
 14. A method, comprising: receiving acall origination request at a carrier gateway server to route a callinitiated from a user device destined for an end user device; querying,by the carrier gateway server, an enterprise gateway server to identifya policy used to route the call; receiving, by the enterprise gatewayserver, a request to route the call to the end user device based on thepolicy; routing the call to a media server; establishing a bearer pathto support the call; and transmitting a ringing indication via thebearer path.
 15. The method of claim 14, wherein a voice over theInternet (VoIP) protocol is used by the media server to route the call.16. The method of claim 14, further comprising routing the call from themedia server to a private branch exchange via the enterprise gatewayserver.
 17. The method of claim 14, wherein the ringing indication istransmitted from the end user device to the user device via the bearerpath.
 18. The method of claim 17, further comprising: establishing amedia path controlled by the enterprise gateway server that is separatefrom the bearer path that operates between a private branch exchange andthe end user device; and connecting the bearer path to the end userdevice via the enterprise gateway server when the end user deviceanswers the call.
 19. A system, comprising: a private branch exchange(PBX) configured to receive an instruction to route a call to a phoneassociated with a mobile station; route the call to the phone and to anenterprise gateway server; and an enterprise gateway server configuredto route the call to a carrier network; notify the PBX that the mobilestation is ringing; and wherein the PBX is configured to cancel the callto the phone responsive to an indication being received that the callwas answered at the mobile station.
 20. The system of claim 19, whereinthe private branch exchange is configured to receive a call originationrequest of the call destined to a member registered with the mobilestation and the phone communicably coupled to the private branchexchange.